In order to achieve standards of low carbon emission and high energy efficiency, power devices are important in electronic devices and power supply systems. In the green energy industries, such as electric vehicle (EV)/hybrid electric vehicle (HEV) industries, distributed power and smart grid industries, and wind power and photo voltaic system industries, power consuming and energy conversion efficiency of devices are critical in power saving Since wide band gap materials, such as silicon carbide (SiC) have high thermal conductivity which is three times the thermal conductivity of silicon, the wide band gap materials can be used or operated in a higher temperature condition and are beneficial to applied to small heat sink module systematization. In addition, SiC has a high withstand voltage and a high critical breakdown electric field characteristic, and a withstand layer can have a higher concentration and a thinner thickness in the devices, such that the devices using SiC have a lower resistance and the turn-on power consuming is reduced. Moreover, because the carrier concentration of SiC is lower than that of Si, SiC has a lower current leakage characteristic and a short response time almost near zero, so that the turn-off power consuming of the devices is lower.
However, the transistor device using SiC still has many problems needed to be overcome, such as insufficient turn-on current of the transistor device, decreasing electric field strength at the gate oxide layer of the power transistor device when a breakdown of the transistor device occurs.